Falling film plasma reactors are frequently used to reduce metallic oxides. In plasma reactors of the falling film type, an arc is struck between a cathode and an anode. The reactants (e.g., metallic oxides and reducing agents such as carbon) are mixed and fed onto the walls of the anode through feedports. The reactants are melted by the heat of the arc and form a film on the anode; this film limits wear of the anode.
Falling film reactors have been employed to reduce metal oxides with high melting points such as Fe.sub.2 O.sub.3 and Fe.sub.3 O.sub.4. However, when the lower melting point oxides such as V.sub.2 O.sub.5 (melting point 800.degree. C.) and B.sub.2 O.sub.3 (melting point 450.degree. C.) are fed into the reactor, the oxides fuse and plug the reactor feedports. For some low melting point oxides this problem has been overcome in part by prereacting the oxides to form higher melting point oxides. For example, V.sub.2 O.sub.5 which has a low melting point can be converted to an oxide with a higher melting point, V.sub.2 O.sub.4. However, other oxides such as B.sub.2 O.sub.3 cannot be reacted to form higher melting point oxides; and thus these oxides cannot be effectively reduced in falling film plasma reactors.
It is an object of the present invention to provide a falling film plasma reactor which overcomes the problems associated with the reduction of low melting point oxides or other low melting reactants.